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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt'>Dear QE developers and users,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>I am trying to run a “relax” structural optimization of the Biotin molecule on QE-5.2.0, the default nstep=50 does complete but I made a few observations on the output file.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>(1) “Check: negative starting charge=   -0.823869” Is this quite large since I have only 90 electrons? Is it expected to be 0.001*90=0.009 or less according to the FAQ. <a href="http://www.quantum-espresso.org/faq/self-consistency/#6.12">http://www.quantum-espresso.org/faq/self-consistency/#6.12</a><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>(2) It ends by the maximum number of steps reached. Is this normal to end BFGS geometry optimization?<o:p></o:p></span></p><p class=MsoNormal style='margin-left:18.0pt'><span style='font-size:11.0pt'>“energy   old            =    -277.9634535886 Ry<o:p></o:p></span></p><p class=MsoNormal style='margin-left:18.0pt'><span style='font-size:11.0pt'>  energy   new            =    -277.9645708192 Ry<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>          CASE: energy  _new < energy  _old<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>          new trust radius        =       0.1278123491 bohr<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>          The maximum number of steps has been reached.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>          End of BFGS Geometry Optimization”<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>(3) I have increased the nstep=100 and 1000,  It only takes long to end the job but still ended by maximum number of steps reached. Which is very strange.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>(4) I have tried to increase  ecutwfc=200.0d0,  ecutrho=800.0d0, then the negative starting charge becomes much smaller to -0.000171<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>(5) How can I speed up this task?<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>Please take a look at the input file as attached. Any comment are welcome.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>Thanks,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt'>Rolly<o:p></o:p></span></p></div></body></html>